Chaotic Spreading Codes for Rate Line Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current spread spectrum communications systems have exploitable features that allow unintended recipients to detect cyclostationary statistics, leading to the discernibility of rate lines, which complicates signal detection and increases bit-error-rates.
Innovation Solution
The use of chaotic spreading codes generated by deterministic systems sensitive to initial conditions, such as the double rod pendulum or Lorenz attractor, eliminates cyclostationary statistics, making it impossible for unintended recipients to determine the underlying symbol rate or code chip rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cyclic spreading codes are used in spread spectrum communications, then the system achieves basic communication functionality, but rate lines become detectable by unintended recipients
Solution Approach 1:
The patent changes the fundamental parameter of the spreading code from cyclic to non-cyclic structure. By using chaotic sequences generated from sensitive dependence on initial conditions, the code eliminates the periodic repetition that creates rate lines, making the signal indistinguishable from random noise and undetectable by conventional methods.
Solution Approach 2:
The patent replaces traditional deterministic cyclic code generation with a chaotic system that exhibits sensitive dependence on initial conditions. This substitution transforms the signal structure from having predictable periodic patterns to having apparent randomness, eliminating rate lines while maintaining communication functionality through synchronized chaotic generation at transmitter and receiver.
2Productivity
If conventional cyclic spreading codes are used, then signal transmission is achieved, but cyclostationary statistics allow detection of symbol rate and code chip rate
Solution Approach 1:
The patent fundamentally changes the statistical properties of the spreading code by eliminating cyclostationarity. The chaotic non-cyclic code removes the periodic correlations that reveal symbol rate and chip rate information, preventing unintended recipients from extracting rate information while maintaining efficient data transmission through the chaotic spreading process.
3Object-generated harmful factors
If filtering is applied to suppress rate lines, then rate line magnitude is reduced, but inter-symbol interference increases causing higher bit-error-rates
Solution Approach 1:
The patent extracts and eliminates the source of rate lines by using non-cyclic chaotic spreading codes instead of cyclic codes. This removes the periodic structure that generates rate lines at their source, avoiding the need for filtering that would otherwise cause inter-symbol interference and increased bit-error-rates.
Solution Approach 2:
The patent converts the apparent randomness of chaotic sequences into a benefit by eliminating rate lines entirely. The sensitive dependence on initial conditions creates signals that are indistinguishable from random noise, which prevents detection while maintaining communication integrity without requiring filtering that would harm signal quality.
Data Source
AI summary
A system, method, and computer program product for chaotically generating a pseudorandom number sequence, such as for use in spread spectrum communications systems and in cryptographic systems. Chaotically generated pseudorandom numbers are not cyclostationary in nature, so output values encoded via such non-cyclostationary bases have no clear correlations. Spread signal communications systems using chaotically generated spreading codes thus operate without rate line artifacts, increasing their resistance to signal detection and to determinations of underlying signal chip rates and signal symbol rates. Broadcasts and guided transmissions (including either conductive wire or optical transmission media), in both radio frequency and optical systems are supported. Common spread spectrum communications systems including DSSS and FHSS may be strengthened through the use of chaotically generated spreading codes. Similarly, keys and nonces generated for cryptographic systems may be improved over those based on conventionally generated pseudorandom numbers.